The short answer
Rev. Proc. 2008-16 is the IRS safe harbor under which a dwelling unit you also use personally will be accepted as property held for productive use in a trade or business or for investment, if you own it 24 months and in each of the two 12-month periods rent it at a fair rental for 14 days or more and keep personal use to the greater of 14 days or 10 percent of the days rented. It applies to the property you sell, measured over the 24 months before the exchange, and to the property you buy, measured over the 24 months after. Outside it, the question is decided on the facts, and the Tax Court has refused exchanges of homes used only personally.
At a glance
| Ownership | At least 24 months before the exchange, or after it for replacement property |
|---|---|
| Rental | 14 days or more at a fair rental in each of the two 12-month periods |
| Personal use cap | Greater of 14 days or 10 percent of days rented at fair rental, each period |
| Effective | Exchanges of dwelling units on or after March 10, 2008 |
The procedure answers one question, investment intent, for homes with mixed use.
Rev. Proc. 2008-16 begins from cases that went against owners. It cites Rev. Rul. 59-229 and Moore v. Commissioner, T.C. Memo. 2007-134, where two lakeside homes used only personally were not held for investment even though the owners expected them to appreciate. It then gives a safe harbor because many owners rent dwelling units but also use them occasionally.
A dwelling unit is real property improved with a house, apartment, condominium or similar improvement providing sleeping space, bathroom and cooking facilities. Personal use is any day counted under section 280A(d)(2), which includes use by you, a co-owner or a family member, and use by anyone not paying a fair rental.
A hypothetical condo shows how the personal-use cap moves with rental days.
Hypothetically, you have owned a beach condo for three years and plan to exchange it. In the 12 months before the exchange you rent it at market rates for 150 days; in the 12 months before that, for 90 days. The caps are 15 days for the later year, 10 percent of 150, and 14 days for the earlier year, because 10 percent of 90 is only 9 and the 14-day floor is greater.
If you stayed 12 days in the earlier year and 15 in the later, you are inside both periods and the safe harbor applies. One extra family weekend in the earlier year would put you outside it, leaving the facts to decide. Count days with your CPA, not from memory.
It bites on the replacement side, because the test runs two years into the future.
For replacement property the 24-month period and the two 12-month periods start the day after the exchange. Section 4.05 says that if you report an exchange expecting to meet the standards and later find the unit does not, you should file an amended return and not report the transaction as an exchange.
Section 4.06 limits the procedure to the investment question; every other requirement of section 1031 still applies. For planning around holiday and short-term rentals, see vacation and short-term rental usage, exchanging a vacation rental and how long to rent before moving in.
Related questions
Does a family member's stay count as personal use?
Generally yes. Section 280A(d)(2) counts use by members of your family, and the procedure adopts that rule; section 280A(d)(3) excludes a rental at a fair rental to someone using the unit as a principal residence.
Is the safe harbor the only way a vacation home can qualify?
No. It is a safe harbor, so a home outside it can still qualify on its facts, but the procedure itself cites cases where homes used only personally failed. Staying inside it removes the argument. See the safe harbor concept.
Does a short-term rental count toward the 14 days?
Days rented to others at a fair rental count. Whether the rate was fair is judged on the facts when the rental agreement is made, under section 4.04 of the procedure.
Sources
Checked against these publications on September 30, 2026. Rules and figures change; confirm the current version with your CPA or attorney before you act. This page is general information, not tax or legal advice.